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I'm trying to integrate my application (Windows desktop app, and Web app) with mobile calendars.

My application is supposed to

  • push new events to mobile calendars
  • fetch events form mobile calendars

So far I managed to integrate with Google calendar (very easy, simple library + OAuth)

Now I want to do the same with iCloud calendar, but it's not that easy.

  • In iCould settings I can make a calendar public. Than I can fetch events (as a iCalendar file), but I cannot push events.
  • The cannot find any serious libraries for iCould calendar integration. I gave CalDav.Client a try, but need to provide CalDAV server url. which according to this should look like" https://pXX-caldav.icloud.com/USER_ID/calendars/CALENDAR_ID. I have no idea what USER_ID and CALENDAR_ID are and where to find them.

Any ideas?

PS

There is a workaround. I can ask user to create a Google accout along with a calendar and use it as a proxy. Integrate IPhone with Google calendar and form the other site integrate my application with Google calendar. It works, but the configuration is kind of tedious for the user.

EDIT

I tried following @hnh's instructions and discover CalDAV this way:

PROPFIND https://p42-caldav.icloud.com/ HTTP/1.1
Depth: 0
Prefer: return-minimal
Content-Type: application/xml; charset=utf-8
Host: p42-caldav.icloud.com
Content-Length: 102

<d:propfind xmlns:d="DAV:">
  <d:prop>
     <d:current-user-principal />
  </d:prop>
</d:propfind>

The result was 401:

HTTP/1.1 401 Unauthorized
Content-Type: text/html;charset=utf-8
WWW-Authenticate: x-mobileme-authtoken realm="MMCalDav"
WWW-Authenticate: basic realm="MMCalDav"
Server: iCloudCalendarServer 15G33
Date: Tue, 26 Jan 2016 12:46:14 GMT
X-Responding-Server: mr26p42ic-ztdg05101801 17 a63660a6f7d1a25b5a7ed66dab0da843
X-Transaction-Id: c8dc19d4-c42a-11e5-8381-008cfaeb448c
Content-Length: 141
Strict-Transport-Security: max-age=31536000; includeSubDomains

<html><head><title>Unauthorized</title></head><body><h1>Unauthorized</h1><p>You are not authorized to access this resource.</p></body></html>

EDIT 2

Following further instructions I managed to authenticate, but still have problems with the requests from the article:

For:

<d:propfind xmlns:d="DAV:" xmlns:cs="http://calendarserver.org/ns/">
  <d:prop>
     <d:displayname />
     <cs:getctag />
  </d:prop>
</d:propfind>

I get: (ctag not found, and displayName with value of "tmp" - which I don't recognize)

<?xml version='1.0' encoding='UTF-8'?>
<multistatus xmlns='DAV:'>
  <response>
    <href>/</href>
    <propstat>
      <prop>
        <displayname>tmp</displayname>
      </prop>
      <status>HTTP/1.1 200 OK</status>
    </propstat>
    <propstat>
      <prop>
        <getctag xmlns='http://calendarserver.org/ns/'/>
      </prop>
      <status>HTTP/1.1 404 Not Found</status>
    </propstat>
  </response>
</multistatus>

And for this:

<c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">
    <d:prop>
        <d:getetag />
        <c:calendar-data />
    </d:prop>
    <c:filter>
        <c:comp-filter name="VCALENDAR" />
    </c:filter>
</c:calendar-query>

I get 400 Bad Request

Andrzej Gis
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1 Answers1

3

This is a nice introduction: Building a CalDAV client. It also describes how the calendar discovery process works (how you find the calendar homeset URL).

Many CalDAV servers do not support OAuth, you'll usually have to ask the user for login/password.

There doesn't seem to be a .NET library for CalDAV. You can find a list of implementations over here: http://caldav.calconnect.org/implementations/librariestools.html.

Summary: Probably not as easy as what you did with Google, but not super hard either. And once you have it, you can connect to many different servers, given that CalDAV is a standard ... (including Google, you can connect to that with CalDAV as well).

Update after the EDIT of the question:

The 401 is a generic HTTP response. It means that you need to provide credentials to continue with the request. A client would usually prompt the user for login/password and then re-run the request. Basic authentication is well described in the Wikipedia article on Basic auth.

Another mistake is to use p42-caldav.icloud.com as the entry point URL. Use caldav.icloud.com as you don't know which partition the user is on. You need to use the discovery process as described in Building a CalDAV client to find the actual URL the users calendar is hosted on.

hnh
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  • What about this part? "I need to provide to CalDAV server url. which according to this should look like" https://pXX-caldav.icloud.com/USER_ID/calendars/CALENDAR_ID." Where can I find USER_ID and CALENDAR_ID values? – Andrzej Gis Jan 26 '16 at 12:05
  • The discovery process doesn't work with iCloud. It requries authorization. I'm not even sure if i'm hitting the right url. ;/ See the edit please. – Andrzej Gis Jan 26 '16 at 12:52
  • I read your answer. I just find the provided link too generic. I'm not trying to do anything using OAuth right now. The problem is I can't find documentation specific to iCloud and knowing CalDAV internals doesn't help me much. – Andrzej Gis Jan 26 '16 at 15:02
  • The link is generic because CalDAV is generic. iCloud is a CalDAV server, you need to implement that to reliably connect to it. E.g. you *have to* implement the Discovery as the URL structure can change, and did so in the past. – hnh Jan 26 '16 at 15:08
  • Ok, I agree, but still I can't find any instructions on the web on what are the iCloud specifications for discovery (i.e. it seems they require some kind of authorization, but I don't know which one) It's not even specified what is their discovery service URL. Maybe I've been hitting an incorrect one and thus I got 401. – Andrzej Gis Jan 26 '16 at 15:20
  • iCloud works exactly as described in the link I posted. You can't discover the users home URL unless you give it credentials. 401 is part of generic HTTP and specified in [RFC2616](https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.2). I mentioned which one you need: Basic. It says so in the response (WWW-Authenticate: basic.). – hnh Jan 26 '16 at 15:26
  • Thanks. That pushed me a little further, but not much. Can you please take a look at EDIT2? – Andrzej Gis Jan 26 '16 at 16:14
  • You are getting the `tmp` thing, because you are hitting `/` (root) instead of a proper CalDAV collection. Do the discovery process as described in `Building a CalDAV client`. This has all the details you need. – hnh Nov 17 '17 at 12:06
  • Hi @hnh , I have a problem in creating new event for iCloud Calendar. Somehow, it always results `400 Bad Request`. I have set `PUT` for the method, set `If-None-Match: *` for the header, used example of content from here `https://tools.ietf.org/html/rfc4791#section-5.3.2` and set this `https://p46-caldav.icloud.com/[USER_ID]/calendars/work/dfsfsdfsfsfsfsdfsdfsdf.ics` as uri destination . Do you have any idea what possibly wrong? – Yusril Maulidan Raji Jun 06 '18 at 11:36
  • in case anyone needs more detail about my question: https://stackoverflow.com/questions/50720196/creating-new-event-to-icloud-apple-calendar-always-results-400-bad-request – Yusril Maulidan Raji Jun 06 '18 at 14:13